Hello there. I've been studying filters and I was hoping someone could help me figure out some details about the filter objects in Pd. I'm mostly concerned about the filter types such as butterworth, chebyshev, bessel and eliptic.

For instance, in [biquad~], can you get all of these 4 types of filter? I guess so... but if it's true, what are the differences in calculating the coefficients? Or perhaps someone could suggest me somewhere to learn about it.

But like, about the filters described at "Cookbook formulae for audio EQ biquad filter coefficients"

http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt

Do any of you know if they're Butterworth or what?

And what about the filters in Pd, I was able to implement with biquad the following objetcs: [lop~], [hip~], [bp~], [lores~] and [reson~]. What types would they be?

I'd also like to hear something about [vcf~].

Well, that's it...

thanks ;)